Account for the following:Aromatic carboxylic acids do not undergo Friedel-Crafts reaction.

Aromatic carboxylic acids do not undergo Friedel-Crafts reactions (both alkylation and acylation) due to several reasons related to the nature of the carboxyl group and the reaction mechanism:

Deactivating Nature of the Carboxyl Group:

The carboxyl group (-COOH) is a strongly deactivating group for the benzene ring. It withdraws electron density from the ring through both resonance and inductive effects. This makes the aromatic ring less nucleophilic and therefore less reactive towards electrophiles.
Coordination with Lewis Acid Catalyst:

Friedel-Crafts reactions typically require a Lewis acid catalyst, such as AlCl₃. Carboxylic acids can coordinate with Lewis acids through their lone pairs on the oxygen atoms. This coordination can form a complex that reduces the effectiveness of the Lewis acid as a catalyst for the Friedel-Crafts reaction.
Formation of Carboxylate Complex:

The carboxyl group can react with the Lewis acid to form a carboxylate anion complex, which further deactivates the aromatic ring and makes it even less reactive towards electrophilic attack.
Reaction Conditions:

The acidic conditions required for Friedel-Crafts reactions can lead to decarboxylation (removal of the -COOH group) of aromatic carboxylic acids, thus destroying the starting material.
Overall, the strong electron-withdrawing effect of the carboxyl group and its interaction with the Lewis acid catalyst significantly hinder the electrophilic aromatic substitution that is necessary for the Friedel-Crafts reaction to proceed.